Numerical Simulation with Comsol and Modeling with Response Surface Method of the Effect of Drying Factors on Dried Apple Shrinkage

This study aimed to combine the response surface methodology and COMSOL simulation to reduce the number of studied treatments, find the effective factors and their interactions and also the prediction model for final dried orange characteristics, and find the shrinkage model of apple fruit concerning the studied drying process factors. A definitive screen design of response surface methodology was designed by Design-Expert software. Factors such as drying time (A: 20-60 ℃), air velocity (B: 0.5-2.5 m/s), sample thickness (C: 3-7 mm), sample diameter (D: 4-6 cm), and drying time (E: 6000-10000s) were investigated. These treatments were simulated in COMSOL software 5.3a. After finding the treatments in Design Expert software, the simulation starts. Results show apple samples results show, that the air temperature and its interaction with other investigated factors, the sample thickness, and the air velocity are effective on the central temperature of the sample. The moisture rate and moisture content are depending on drying time. Apple shrinkage is a logarithmic model as a function of air temperature, sample thickness, and process time. Apple shrinkage during drying significantly affects the thickness of samples. To control the shrinkage rate during apple drying, controlling the time of process and sample thickness is more effective than other processing factors. This leads to a prediction model for drying apples and process control. The optimization is shown the minimum shrinkage is at 0.7mm thickness, 5.45cm diameter, and 9938s process time.